Physiological Response And Adaptability Of Five Shrub To Drought And Saline-alkaline Stress In The Western Expressway Of Heilongjiang Province

Qitai Highway is located in the arid and semi-arid areas of Songnen Plain. It is the third soda saline and alkaline land in the world. Selection of drought-tolerant and saline-alkaline tolerance plants applied to slope eco-engineering has great significance in preventing the highway slope from soil erosion, enhancing the stability of the roadbed and ecological restoration of highway surroundings. In this paper, two-year-old seedlings of Amorpha fruticosa,Tamarix chinensis, Caragana microphylla,Fructus Hippophae and Hedysarum fruticosum var. mongolicum were taken as test materials, which were individually treated with five moisture gradients(control, mild stress, moderate stress, severe stress and extremely severe stress) by controlled irrigation. Sample after21days. Which were individually treated with four saline-alkaline gradients(control,0.5g/kg,1g/kg,1.5g/kg) by controlled irrigation sample after6days, the conductivity, total chlorophyll content、activity of SOD, content of MDA, soluble sugar content and proline content of the seedlings leaves were determined in order to investigate the drought-resistant abilities of the three kinds of seedlings mentioned above. For the western region of heilongjiang province highway slope greening provide theoretical basis.The results showed that with the prolonged drought, the RPP of five kinds of shrubs leaves presented decreased in the beginning and then increased. In saline-alkaline stress, the RPP of five shrubs leaves have no decrease trend, just slow down the rising of RPP in a certain degree, because Na+enter into leaf cells, replace Ca2+in cell membrane, make eukaryotic cell structure changed to hurt the shrub. Shrubs recover membrane permeability by itself with the prolonged drought, but membrane permeability can’t recover under saline-alkaline stress.With the drought stress become serious, total chlorophyll content of five seedlings increased in the beginning and then decreased, but total chlorophyll content on a declining curve in saline-alkaline stress. Total chlorophyll content1.5g/kg level in saline stress more than extremely severe stress level in drought-tolerant. So the primary cause total chlorophyll content reduce is drought-tolerant.With the drought stress become serious, SOD activity of five kinds of seedlings increased in the beginning and then decreased, but SOD activity has been raised in saline-alkaline stress, The maximum SOD activity of Amorpha fruticosa,Tamarix chinensis and Caragana microphylla,under drought stress more than saline-alkaline stress, saline-alkaline stress SOD on shrubs protection is greater than the drought stress. Five kinds of shrubs blade soluble sugar and proline content shows a ascendant trend, Shrubs by increasing the soluble sugar and proline content maintain cell osmotic balance against bad habitat. The physical signs between control and severe stress on highway slope. The physical signs between control and0.5g/kg stress level in saline-alkaline stress. The drought stress injure to shrubs more than saline-alkaline stress.Through subordinate function analysis on five kind of shrubs, the order of drought-resistant abilities of the five kinds of shrubs was:Amorpha fruticosa>Caragana microphylla>Hedysarum fruticosum var. mongolicum>Tamarix chinensis>Fructus Hippophae the order of saline-alkaline-resistant abilities of the five kinds of shrubs was:Amorpha fruticosa> Hedysarum fruticosum var. mongolicum> Tamarix chinensis> Fructus Hippophae>Caragana microphylla. Amorpha fruticosa, Caragana microphylla, Hedysarum fruticosum var. mongolicum suitable for planting in severe drought slope. Amorpha fruticosa, Hedysarum fruticosum var. mongolicum and Tamarix chinensis suitable for planting in saline-alkaline slope.